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The 180th meridian or antimeridian [1] is the meridian 180° both east and west of the prime meridian in a geographical coordinate system. The longitude at this line can be given as either east or west. On Earth, the prime and 180th meridians form a great ellipse that divides the planet into the Western and Eastern Hemispheres.
The division of Earth by the Equator and the prime meridian Map roughly depicting the Eastern and Western hemispheres. In geography and cartography, hemispheres of Earth are any division of the globe into two equal halves (hemispheres), typically divided into northern and southern halves by the Equator and into western and eastern halves by the Prime meridian.
Direction determination refers to the ways in which a cardinal direction or compass point can be determined in navigation and wayfinding.The most direct method is using a compass (magnetic compass or gyrocompass), but indirect methods exist, based on the Sun path (unaided or by using a watch or sundial), the stars, and satellite navigation.
A position in the equatorial coordinate system is thus typically specified true equinox and equator of date, mean equinox and equator of J2000.0, or similar. Note that there is no "mean ecliptic", as the ecliptic is not subject to small periodic oscillations. [5]
In geography and geodesy, a meridian is the locus connecting points of equal longitude, which is the angle (in degrees or other units) east or west of a given prime meridian (currently, the IERS Reference Meridian). [1] In other words, it is a coordinate line for longitudes, a line of longitude.
In geography, the antipode (/ ˈ æ n t ɪ ˌ p oʊ d, æ n ˈ t ɪ p ə d i /) of any spot on Earth is the point on Earth's surface diametrically opposite to it. A pair of points antipodal (/ æ n ˈ t ɪ p ə d əl /) to each other are situated such that a straight line connecting the two would pass through Earth's center.
The 45×90 points are the four points on Earth which are both halfway between one of the geographical poles and the equator, and halfway between the Prime Meridian and the 180th meridian. Both northern 45×90 points are located on land, while both southern 45×90 points are in remote open ocean locations.
The latitude of the Earth's equator is, by definition, 0° (zero degrees) of arc.The equator is one of the five notable circles of latitude on Earth; the other four are the two polar circles (the Arctic Circle and the Antarctic Circle) and the two tropical circles (the Tropic of Cancer and the Tropic of Capricorn).